Tanks & Equipment

How Big of a Tank Do You Need for Betta Fish?

When it comes to the size of a Betta fish tank there is a lot of online debate between Betta fish owners, breeders, veterinarians and animal care activists. Betta fish are often kept in small bowls, flower pots or glasses. Some do survive and live long, happy lives, so it is often unclear to the owners why they have to buy bigger tanks, when in their experience a flower vase is good enough. 

If you have a Betta fish as a pet or are planning to get one, you have probably researched all about proper care online and come across confusing or contradictory information, and  not sure who to trust. 

The first thing you should pay attention to is their home, that is, the fish tank. Pet stores, as well as breeders – often keep Betta fish in small plastic cups or very messy aquariums. Although the general opinion is they can survive bad conditions – that is not entirely true.

It is true though that Betta fish are hardy and thanks to their aggressiveness, they managed to survive in not ideal conditions in nature. 

They are tropical fish and any extreme deviation from a similar environment for a long period is fatal for them. 

How Big Is Big Enough?

So, no matter how many people convince you that Betta fish are so cool that they will enjoy a small aquarium – it’s just not like that.

Like all fish of any size and species – Betta fish like to swim in as large a space as possible. 

So, the smallest optimal tank size for just ONE Betta fish is the three-gallon. 

Anything below that size is too small for a Betta fish or any fish. The ideal size of the aquarium is 5 gallons for one Betta, and if other conditions are optimal your Betta fish will live 5 long fish years there. 

The average lifespan of a Betta fish is 3-5 years. If Betta lives in a small aquarium, in a water of inappropriate temperature – it will probably die in a few months at most.

If you are planning to create a mixed aquarium with Betta fish and other fish species, it is clear that the aquarium must be as large as possible.

In addition, all fish must be compatible by character and environmentally. 

You will need a gallon for every extra fish in the aquarium. Some experts point out that ONE gallon refers to one gallon per inch of an adult fish. It makes sense, because fish are living beings, with all their virtues and flaws. They can be moody, aggressive, swim or hide and rest. That is why an aquarium and water alone are never enough.

Why Do I Need A Three-Gallon Aquarium If I Only Have One Betta Fish?

Betta fish are living beings that have adapted to nature during evolution and have survived to this day. No animal or man is happy if they are in a small space, where they cannot be in harmony with themselves – so the Betta fish is not happy in a small aquarium. 

Such a small water space restrains their body created primarily to swim. Also, Betta fish are specific because they have evolved enough to be anabantids – a species of fish that, in addition to its gills, can, like terrestrial animals, take oxygen from the air. 

They swim to the surface of the water and take oxygen through the organ named “labyrinth”. 

Breeders and owners often thought that due to the labyrinth Betta fish could be kept in small aquariums or bowls. That is how they became a decoration for the office desk and small apartments. Also, the water in a small aquarium gets dirty quickly. Frequent cleaning, almost daily, additionally stresses the fish and in such an environment, it will quickly become too nervous or lethargic.

Frequent water changes do not allow “good” microbes to develop. These are the ones that help maintain a healthy ecosystem and one of the reasons why you can’t pour distilled water into an aquarium. Good microbes are the roles of cleaners and waste decomposers. They help make the water healthier, i.e. optimal for fish.

Can I Create Proper Conditions In Smaller Fish Tanks?

Smaller fish tanks are good for a short time. For instance you can use them when you want to gradually adapt Betta fish to a new environment or to move female Betta after mating. If, after all, you decide to use a small fish tank – you will have to be very cautious. 

The general recommendation for small fish tanks is to use Nano filters, but they are often too large and take up a lot of space in an already small aquarium. This is why most opt ​​for frequent complete or partial water changes. 

However, if Betta fish somehow avoids all that great stress, even frequent water changes do not guarantee that the conditions are optimal.

Also, in a very small aquarium, it is more difficult to maintain the optimal temperature. The water overheats or gets cold quickly, plus an additional heater and thermometer take up most of the aquarium. Even if you somehow manage to regulate all this, keeping any fish in a one-gallon aquarium is inhumane and unethical.

Is It Harder To Maintain A Smaller Or Larger Fish Tank?

Although simple logic leads to the conclusion that smaller fish tanks are easier to maintain – in this case the situation is reversed.

You have to put in a lot of effort every day to keep the smaller fish tank clean and warm enough for the fish to survive. As already mentioned, frequent water changes do not allow microbes and fish to create a mini-ecosystem that would be partly self-sustaining. In a one-gallon aquarium, that is impossible. 

You have to constantly watch out for the aquarium and the fish and for the dirt. It is a constant weekly job, if not a daily one because in such conditions a lot of things can go wrong. Dirt from excess food, and even if you think it is a slight excess, in a small space it quickly becomes a source of infection and disease for fish. 

Also, there are algae, which grow better in water but can harm Betta fish. A common disease in Betta fish is fin rot – which mainly occurs in small aquariums. Even with the best will and regular observation, something can always go wrong. In the end, you spend more time creating optimal conditions for your fish than you enjoy its presence. 

Larger aquariums are much more expensive, but also better equipped, so they basically do a good deal of the work for you.

By comparison, smaller aquariums and bowls need to be cleaned at least once a week, while a 55-gallon aquarium only takes you 30 minutes a month.

Since Betta fish are known as jumpers, you can also get an aquarium with a lid. If you want more fish of different species – a large aquarium is a must. In such a fish tank – there can be only one male Betta fish.

Fish Tank Maintenance

Before you put the Betta fish into her new home – all the conditions must be at the optimal level. The aquarium, in addition to the appropriate size, must be clean, with water of the appropriate temperature and quality, have a filter, heater, thermometer, and carefully selected accessories such as gravel, stones, and plants.

A liquid water conditioner can be found on the market to remove chlorine from the water. For betta fish, the optimal conditions are pH around 7.0, GH 7-9º, KH 5-8º. You can also use supplements such as GH ‘General Hardness’ and KH ‘Carbonate Hardness’. Regular analysis and checking of water for pH, GH, KH, and ammonia nitrite is a very important part of aquarium maintenance rules. The optimum water temperature is between 74 and 82 degrees Fahrenheit.

Betta Fish Tank

Partial water replacement, up to 10% is necessary to do once a week. You can use vacuum gravel to collect waste and excess food. It is also good to wipe the sides of the aquarium with a special fish tank sponge and wash the decorations.

Place the fish tank as far away from sunlight as possible; thus preventing overheating and algae growth. The lights in the aquarium must be turned off for 12 hours a day for the fish to rest, and also to reduce the chance of algae developing.

Betta fish love plants. They help them to rest, but also to increase their curiosity. Healthy Betta fish will swim around the plants, explore and thus neutralize stress and reduce natural aggression. 

You must make sure that the plants are not too thick and not sharp; otherwise they could injure the fish. Be careful not to completely cover the surface of the water with plants, because Betta fish must take oxygen from the air and free passage to the surface is necessary. You can also plant artificial plants. The only thing that matters is that they are not rough and sharp.

Pebbles or any accessories must have soft and smooth edges and surfaces. Do not put a mirror in a fish tank with a male Betta fish. He interprets his reflection as a rival, which can lead to increased aggression and injuries.


There is always a better and more humane choice – a bigger fish tank. If you do not have the conditions to buy and maintain a large aquarium, it may be better to choose another pet. However, if you decide to buy a Betta fish – try to provide it with the best possible conditions.